Intel Core i9 7900X processor review -
Final Words & Conclusion

Final words & conclusion

The year 2017 turns out to become the most exciting year for desktop processors since maybe even a decade. AMD released Ryzen, Intel reacted. Then all of the sudden it became apparent that AMD had a hidden high-end desktop processor called Threadripper, and once again Intel needed to adapt. Shortly after the Threadripper announcements Intel all of the sudden pulled a rabbit out of its hat by announcing processors up-to 18 cores. However that turned out to be what we call a paper-launch, it looks good but there is no such part to be found anywhere. Realistically though Intel is doing what it has been doing so often, reinserting refreshed SKUs. In this case up-to 10 cores is what you can purchase, much like last years Core i7 6950X processor. The new Core i9 7900X however has improved on IPC a bit, but more overly Intel addressed the turbo boost modes by introducing a Turbo boost 3.0 mode. If you need less cores then two cores can turbo to 4.5 GHz. And that's where things get interesting as less threaded games will benefit from that in the lower resolutions like 1080p, and that is a bit of an Achilles heel for AMD (albeit very relative as CPU bottlenecks in lower resolutions always have been there).

Performance & tweaking

For our testing we used the MSI X299 motherboard and I'd rate the new 10-core part as "very good" for the results as tested. Temps remain (borderline) OK (depending on choice of cooling and depending on pstates the motherboard manufacturers uses) however temperatures when the CPU is overclocked with added voltage definitely are a challenge opposed to the last-gen Broadwell-E. BTW if you already are on that platform, really there's little to get excited about upgrading wise. In fact i find my 10-core Core i7 6950X / X99 to be running much better opposed to what we have tested today. At the OC level you are looking at up-to 1.30~1.35V needed on that CPU core (LCS cooling). Now I do have to state that I have been using an ES sample so I cannot say anything conclusive on the final retail products (these might run cooler). The infrastructure that X299 offers is easy to use, you increase the CPU voltage and multiplier and you are good to go. Another plus for the Intel platform is that over the years they have been able to refine their memory controllers, pop in anything XMP 2.0 and you have a 90% change it'll work straight out of the box with very fast memories. However, the effect of fast clocked memory is far less significant for Intel opposed to AMD Ryzen. Also with quad-channel memory available as an option, we'd always suggest to go with a nice affordable 2677 MHz kit, as bandwidth on quad-channel simply is just not relevant in your gaming experience.

Power consumption

With ten cores you get a 140 Watt TDP processor, and I do not believe for a second that value is correct. With the system at idle with a GeForce GTX 1080 installed / 16 GB memory / SSD and the X299 motherboard I hovered at roughly 75 Watts in IDLE. That's just fine really, but the load values are rather significant. When we stressed the processor 100% run we reach roughly 250 to 300 Watts with this is a 10 core part. So we go from 75 Watts towards 300, that's 225 Watt in my book. When we game we hover at ~350 Watts with the GeForce GTX 1080, but obviously that factor is dependent on the type of graphics card you use of course and sure, most games certainly do not utilize the 10 CPU cores.

Issues - Hardware P states

I won't lie, the past two weeks with the Core i7 7900X and the X299 boards I have tested have been an absolute challenge. Memory XMP profiles would not stick, power consumption with one BIOS was OK, the other through the roof. But most of all the processor performance was all over the place. We've seen perf differences of up-to 20% in-between merely different motherboards. MSI however with it's latest BIOS seems to have found equilibrium. Now the biggest fight the two weeks was ironically game performance, it was severely lacking. Example a platform like this should run Rise of the Tomb Raider at 140 FPS at 1080p on a GeForce GTX 1080. We'd end up at 90~100 FPS. And that problem occurred with pretty much all games. I have been discussing this with the motherboard partners (as yes it is widespread) and we all agreed, it has everything to do with 'hardware P states' that Intel recommends to leave enabled for the new platform. Intel recommends certain power states to keep the TDP in line, as otherwise they simply cannot achieve that 140W TDP. For most overall tests that worked out okay enough, but specifically the toll on game performance was abysmal. Days before this launch MSI however released and provided a new BIOS, this restored the performance to what it needs to be. But as you have been able to see, the power consumption is certainly on that high-side. In the end though, the performance is there, but we do expect several BIOS updates that will have an effect in performance overall, in gaming and on power-consumption.

Bothersome

Two things I find to be significantly bothersome, this launch is clouded by too many architectures and processors that really haven't been released. You can choose from 4 to 10 cores, which is fine. However Intel went big with announcement on 12, 14, 16 and even a 2000 USD 18-core part. The 12-core version should see the light next month, however the last three are nowhere to be found and I am starting to doubt that you'll see them anytime soon. The latest indication is October. Sure perhaps a review here and there to show off that Intel can do it. But retail availability? I don't know man. So this all is cloudy and confusing really. But hey, this article hopefully cleared that up or at least made the topic more understandable. We have to discuss PCI-Express lanes. Here is the breakdown:

Kaby Lake-X quad core get 16 PCI-Express Lanes 3.0

Skylake-X six and eight core procs gets 28 PCI-Express Lanes 3.0

Skylake-X ten core procs gets 44 PCI-Express Lanes 3.0

So here we have the most expensive enthusiast class processor and X299 chipset series from Intel. The X299 will be like 250~300 USD, when you spend 599 USD on an eight-core processor. So in the year 2017 you still cannot run two graphics cards at a full x16 PCI-Express lanes, as there are too few available lanes available. Not even the 900 bucks you would spend on an 8-core part, as it will bog down towards two x8 links. Not a biggy I know, but really it is the year 2017 right? For M2 units the chipset offers plenty additional x3 Gen 3 lanes though.

So yeah, value for money wise a thing or two can be discussed alright. I made a plot, this is purely based on the Cinebench multi-threaded score:

So in the above a mathematical plot, we take the CB score from CineBench 15. We normalize the value and basically plot how much money it takes to calculate the CB score. All processors are clocked at default frequencies, this plot would look different if you'd math in tweaked clock frequencies and thus get higher CB scores. Also you need to take the number of CPU cores into account (as in what number of CPU cores is relevant for you). But this is very simple math, have a peek at the chart (the higher a CPU is positioned the better).

So what are you seeing?:

An 8-core Core i7 5960X costs 79 cents per calculated CB.

An 8-core Ryzen 7 1800X costs 25 cents per calculated CB.

A 6-core Ryzen 5 1600 costs just 19 cents per calculated CB.

A Core i9 7900X costs 42 cents per calculated CB.

Value for money wise (Cinebench) shows that the entire Ryzen lineup offers the perf you get in return for your money (prices are based on Euro street prices and MSRP is a CPU is not available). Again this is a fairly subjective chart as it is based on just one test, but it does paint a certain picture. And please do not confuse the chart as to 'what is the better processor'.

DDR4 Memory

Ever since Haswell-E was released along came DDR4 memory. With Skylake-E DDR4 may be clocked a notch faster at 2,677 MHz. Honestly, if you pick up some nice 2,133 MHz DIMMs, at quad-channel it'll offer more than plentiful bandwidth. A 3,200 MHz kit for example is far more expensive and does offer better bandwidth but the performance increases in real-world usage will be hard to find. Unless you transcode videos over the processor a lot. DDR4 mostly was released for lower voltages and higher frequencies. 2,133 MHz CL 14 or CL 15 memory in combo with quad-channel will already get you to 50~60 GB/sec. While impressive to observe for gaming you will not notice huge performance improvements with high memory bandwidth, but with content creation and video transcoding this kind of bandwidth certainly does make a difference. As always, my advice would be to go with lower clocked DDR4 memory with decent timings, but get more of it. Don't go for 8 GB, get four DIMMs and in total a minimum of 16 GB.

The bottom line

The year 2017 is an exciting year in the processor arena. There are many things happening from the two primary brands, both keep each other in line and for the first time in a long time, both offer something very competitive. AMD Ryzen and its platform currently is extremely good. The X299 Core X platform (when all bugs are ironed out) can be exceptional (but right now is very mediocre). AMD however has the upper hand in value and energy efficiency. I mean for the money of one Core i9 7900X processor (1000 USD) and a X299 motherboard (say 250 USD) you can built two Ryzen 7 8-core systems. Intel however has an advantage in its clock-frequencies, they can run a higher number of CPU threads higher clocked compared to the Ryzen processors and it is here where they gain performance in lower resolution gaming. However gaming wise your money is better spend on a fast(er) GPU opposed to a super-expensive CPU though, hey it's the truth.

So more or less cores? In my opinion the age of the quad-core processor is an dying one. AMD sparked and ignited something in the processor and developer landscape with the release of affordable Ryzen 8-core parts. If you look for more value, I find the 6-core parts to be the better balance for what is realistic for today's gaming PCs relative to pricing. But sure, it will be hard to beat the multi-core performance the Core i9 7900X processor offers, if only all software would benefit from 10-cores. Obviously you'll get three other choices as well, the 8 and 6 core processors (which are priced much better). Then there is Kaby Lake-X with four cores as well, how come the Kaby Lake-X processors have pretty much the same specs as the Kaby Lake versions but have a way higher TDP? They don't even have an IGP. Kinda weird right? So yes Intel is fighting energy efficiency at all levels.

Back to my thesis, currently I feel the six- and eight-core parts are probably the most interesting model if you are not that transcoding / ray-tracing / workstation type of user. Today, however, is all about that 10-core product, the Core i9 7900X. The processor itself surely is attractive from every way that you look at it aside from the price level and that weird power states / perf / power consumption variations. The 10 cores bring a massive amount of performance with fast per-core performance up-to a Turbo frequency of 4.3 and 4.5 GHz per core depending on the Turbo mode that is active. Worthy noting is that we reached 4800 MHz on all cores. But the processor at that point will run hot, very hot. This top processor SKU offers a proper 44 PCI Express Gen 3.0 lanes, the hardcore multi-GPU discrete savvy users will be pleased. That however is not the case with the Core i7 7820X, Core i7 7800X (28 lanes), Core i7 7740X and Core i5 7640X (with an almost shameful low 16 lanes). Luckily the chipset will add more for your storage though. DDR4 memory up-to 128 GB can be installed. What if you are already on Haswell-E or Broadwell-E? Well, there's little reason to upgrade really. In the current state the Core i9 7900X is promising. The and all X299 platforms will see a number of BIOS updates though, that I guarantee you.

With the currently tested processor and X299 motherboard Intel certainly will have the slightly better and faster clocked processors compared to AMD. However we'd honestly recommend you to wait and see what AMD is going to offer with Threadripper processors. These will become available this summer in 12, 14 and 16 core models, perhaps at half the price of that Intel is offering. Intel will have their 14, 16 and 18 cores (2000 USD!) processor available in retail later this year. The four up-to 10 core processors can be pre-ordered starting June 19th. The 12-core SKU will be available late August. The 14, 16 and 18 cores models (likely) in October. In its current state X299 / Core i9 7900X is promising, but far from a finished platform. The X299 platforms will see a number of BIOS updates, that I guarantee you. Currently the platform does consume a lot of power, but here again that might be solved and ironed out over time with firmware updates or board partners switching to different power states (at the cost of performance). Yeah, like I stated: it is an interesting year in the HEDT processor market alright. Intel deals a strong hand with the 7900X, especially the high Turbos work out well for them. Again, I do expect to see some weird things with the hardware p-states and motherboard manufacturers. Some will abide to what Intel wants, which would keep power consumption under control at the cost of game performance. Others (like MSI) don't and will offer you full game perf at the cost of energy efficiency. Quite honestly, it might be worth the wait and check what Ryzen Threadripper will offer. Let's hope that AMD can pass the 4.0 GHz marker on Turbos as well.

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